Scientists pinpoint reason for unusual Hawaii tsunami from Canada

Plate shift blamed for unexpected waves

Published  7:24 AM HST Oct 31, 2012
Tsunami computer model
HONOLULU -

"We get data from about 400 seismic stations around the world," said Chip McCreery, director of the Pacific Tsunami Warning Center.

Those stations quickly marked the 7.7 Canadian earthquake. The Queen Charlotte Islands is an active area, but an area that no one thought would, or could generate a tsunami.

"There's going to be a lot of study here. The area is very much like the San Andreas fault where one side is moving next to each other," said geophysicist and seismologist Rhett Butler.

Or so they thought. It turns out that the plates in that area are indeed pushing together, but that means trouble.

"In the Aleutians we have these big thruster earthquakes, and the thruster earthquakes are what cause the big tsunamis because you're moving a lot of the sea floor," said Butler.

Scientists had to rely on tidal gauges along the west coast, thousands of miles away.

During the Japan tsunami, they could also rely on gauges positioned on islands trailing toward Hawaii to get more accurate information before the wave hit.

"We didn't have readings in the right places," said McCreery.

To make matters worse, he said most deep sea gauges were nowhere near the tsunami's track.

He said it is an expensive and limited resource, positioned in areas more likely to generate a real threat.

"So one of top things on our list to discuss is can we reposition these instruments to cover an area like this," he said.

Scientists say more surveys of the shape of the ocean floor right around the islands and our coastlines will help them better calculate what will actually happen as a tsunami close in.

"The science of being able to forecast tsunamis is constantly evolving," said McCreery.

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